The present invention relates to a warning system for warning a lack of a working fluid of an engine.
One typical example of the conventional warning system for an industrial engine is disclosed in Japanese Patent (unexamined) publication 62(1987)-26379, for example. In this earlier attempt, the engine is stopped by a fluid level warning circuit electrically connected to an ignition device when a lack of the working fluid, for example, a lower limit of an oil level is detected.
Japanese patent (unexamined) Publication 62(1987)121833 teaches an attempt to provide a warning when an abnormality of an engine is detected. In the prior art, a warning device is connected in series with an engine abnormality detecting circuit and is supplied with an electric power by an ignition circuit. When an abnormality of the engine is detected, an electrical load for warning, such as a light emitting diode (hereinafter referred to as LED), is driven and the engine is stopped.
In small engines such as industrial engines (for utility), voltage is applied from a magneto to an ignition circuit. In this case, current which flows in the ignition circuit decreases when the LED is lit. This is because relatively large current is needed for lighting the LED. Thus, ignition energy for the ignition circuit decreases, so that hunting of the engine may take place.
For this reason, it is necessary to stop the engine simultaneously with the lighting of the LED when a lack of an engine oil is detected. However, when there is enough time until an engine trouble occurs after the engine oil decreases to a predetermined oil level, it is preferable not to stop the engine at once for continuing a work using the engine.
To overcome this problem, a separate power source such as a lighting coil may be provided other than the magneto, and the LED may be lit by the separate power source. However, the separate power source rather increases cost of the warning circuit.